The invention relates to shock absorbers for improving the safety in passenger compartments of motor vehicles during during impact accidents, preferably for reducing impact between the outer skin of bodywork parts such as doors, and the associated inner lining in the passenger compartment.
There has been no lack of suggested and actually realized projects in the prior art for improving the safety for drivers in their motor vehicles. In this connection, the development of special crush zones which reduce the frontal impact, and stiffening roll bars which ensure greater chances of survival during overturning of vehicles during accidents, are worthy of mention.
The improvement in side impact protection is also gaining increasing importance in motor vehicle technology. Reinforcing profiles or tubular constructions are located under the external skin, especially in the door shells. In supplement to this, it is known to insert between the outer skin and the inner lining, shock absorbers in the form of hard foam molded parts. Such shock absorbers have the advantage of fulfilling a double function during an accident. On the one hand they contribute to absorbing the impact energy, and on the other they are intended to reduce impact forces occurring on the occupants of the vehicle, particularly in their pelvic areas. In order to satisfy both requirements, however, it is necessary as a force-path characteristic in impact absorption to rapidly reach a predetermined power absorption level. This level is to be maintained to a large extent over the impact path. In general engineering, dangerous machine overloads are avoided by the deformation of impact pots specially provided for this purpose. Because of the relatively short impact paths between bodywork metal and internal lining, the use of conventionally constructed impact pots as side impact protection in motor vehicles is problematic, and has to date not even been regarded as approximative. Impact pots to rapidly in an uncontrolled manner can penetrate in certain areas through the inner lining members used in motor vehicles. Therefore, this method has been avoided for this reason alone. In a later side impact, previous impact pots could for this reason offer little protection; and they would instead lead to an additional risk, e.g. by splintering or cold fracture.
For this and other reasons, therefore, efforts to improve side impact protection have been concentrated on an appropriate force coupling between the bodywork metal and the internal lining by using hard form elements, even though only a relatively poor force-path characteristic with regard to impact absorption could be obtained with these elements. In the first portion of the impact path available, the force absorption is small and subsequently the transmission of force increases disproportionately steeply.